mineral

Ethiopian Opal (Welo Opal in Matrix)

Hydrated Silica (SiO2·nH2O)

Hardness: 5.5-6.5 on Mohs scale. Color: Translucent body with 'play-of-color' (iridescence). Luster: Vitreous to waxy. Structure: Amorphous (non-crystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 1.9-2.3.

Hardness: 5
Color: Translucent body with 'play-of-color' (iridescence)
Luster: Vitreous to waxy

Identified March 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the precipitation of silica-rich water in volcanic ash or rhyolite cavities. Most Ethiopian specimens (Welo opals) date from the Miocene epoch, approximately 15-20 million years ago.

Uses & applications

Used primarily in the jewelry industry as gemstones (cabochons) and highly sought after by mineral collectors for their intense color flashes and unique hydrophanous properties.

Geological facts

Many Ethiopian opals are 'hydrophane,' meaning they can absorb water and change transparency or color when soaked. They were first discovered commercially in the late 1990s and 2008 in the Wollo Province.

Field identification & locations

Identify by looking for a 'nodule' or 'egg' appearance with an outer rhyolite matrix crust. In the field, look for 'potch' (common opal) or flashes of color inside weathered volcanic rocks in high-altitude plateau regions.

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